Question: Which extinct language is the indigenous to the Khazars?
Paraphrase: What is the name of the extinct language that is indigenous to the Khazars?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P2341 wd:Q173282 . ?sbj wdt:P31 wd:Q38058796 } 
Answer: Khazar